Technical Field
The present invention relates generally to a method of and system for stabilizing a subterranean rock formation during subterranean mining operations, and, in particular, but not by way of limitation, to coal mine roof stabilization and control.
History of Related Art
Mining for coal or other minerals located beneath the Earth's surface requires a variety of operational issues. In particular, the structural integrity of a subterranean mine (hereinafter referred to as a “mine”) is of great concern. Longwall mining has been used to recover coal from beneath the Earth's surface for decades. Typically, longwall mining refers to a process of removing coal from along a face of coal or a stratified mineral deposit. Once the longwall is exposed, a machine may be used to shear off a portion of the face of the mineral deposit. The sheared off portion is then removed, for example, by a conveyor belt.
Due to enormous pressure that is exerted by the surrounding rock formation above a mining tunnel, it is sometimes difficult to maintain the integrity of a roof within the mining tunnel. Various systems have been developed to increase the stability of roofs within the mining tunnels. An exemplary system includes a use of a plurality of hydraulic jacks, wood supports, or steel supports secured between a floor and the roof of the mine tunnel. Typically, the plurality of hydraulic jacks are placed in a line along a face of the longwall to reduce a likelihood of a cave-in and protect around an area of the longwall face. As more of the face is removed from the longwall, the plurality of hydraulic jacks are moved closer to the face of the longwall in order to ensure stability of the roof near the face of the longwall.
In some mining efforts, as the plurality of hydraulic jacks are moved towards the face of the longwall, the portion of the roof that becomes unsupported as a result of moving the plurality of hydraulic jacks is allowed to cave-in. This area is typically behind the plurality of jacks and away from the direction of mining.
After it has been determined that enough of a coal seam has been removed, it is desirable to remove the mining equipment from the mining tunnel. In some mines, a surrounding rock formation in which the mine has been created may be weak or water saturated. Typically, weaker formations such as, for example, water-saturated sandstone do not support very well when mining tunnels are formed beneath it. In such mines, removing support structures such as, for example, the plurality of hydraulic jacks used for longwall mining, becomes very difficult and dangerous. Therefore, it would be beneficial to provide a method of and system for supporting a surrounding rock formation above support structures to facilitate removal of the support structures such as, for example, hydraulic jacks from a takedown room for a longwall mine.